完成

golang-learning/10-projects/01-calculator/calculator/history.go

@@ -0,0 +1,244 @@
+/*
+history.go - 历史记录管理
+定义了历史记录的数据结构和相关功能
+*/
+
+package calculator
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"strings"
+	"time"
+)
+
+// HistoryRecord 表示一条计算历史记录
+type HistoryRecord struct {
+	Expression string    `json:"expression"` // 表达式
+	Result     float64   `json:"result"`     // 计算结果
+	Timestamp  time.Time `json:"timestamp"`  // 计算时间
+}
+
+// NewHistoryRecord 创建新的历史记录
+func NewHistoryRecord(expression string, result float64) HistoryRecord {
+	return HistoryRecord{
+		Expression: expression,
+		Result:     result,
+		Timestamp:  time.Now(),
+	}
+}
+
+// String 返回历史记录的字符串表示
+func (h HistoryRecord) String() string {
+	return fmt.Sprintf("%s = %g (计算时间: %s)",
+		h.Expression,
+		h.Result,
+		h.Timestamp.Format("2006-01-02 15:04:05"))
+}
+
+// HistoryManager 历史记录管理器
+type HistoryManager struct {
+	records  []HistoryRecord
+	filePath string
+	maxSize  int
+}
+
+// NewHistoryManager 创建新的历史记录管理器
+func NewHistoryManager(filePath string, maxSize int) *HistoryManager {
+	return &HistoryManager{
+		records:  make([]HistoryRecord, 0),
+		filePath: filePath,
+		maxSize:  maxSize,
+	}
+}
+
+// Add 添加历史记录
+func (hm *HistoryManager) Add(expression string, result float64) {
+	record := NewHistoryRecord(expression, result)
+	hm.records = append(hm.records, record)
+
+	// 限制历史记录数量
+	if len(hm.records) > hm.maxSize {
+		hm.records = hm.records[len(hm.records)-hm.maxSize:]
+	}
+}
+
+// GetAll 获取所有历史记录
+func (hm *HistoryManager) GetAll() []HistoryRecord {
+	// 返回副本以防止外部修改
+	records := make([]HistoryRecord, len(hm.records))
+	copy(records, hm.records)
+	return records
+}
+
+// GetLast 获取最近的 n 条记录
+func (hm *HistoryManager) GetLast(n int) []HistoryRecord {
+	if n <= 0 {
+		return []HistoryRecord{}
+	}
+
+	if n >= len(hm.records) {
+		return hm.GetAll()
+	}
+
+	start := len(hm.records) - n
+	records := make([]HistoryRecord, n)
+	copy(records, hm.records[start:])
+	return records
+}
+
+// Clear 清空历史记录
+func (hm *HistoryManager) Clear() {
+	hm.records = make([]HistoryRecord, 0)
+}
+
+// Count 获取历史记录数量
+func (hm *HistoryManager) Count() int {
+	return len(hm.records)
+}
+
+// SaveToFile 保存历史记录到文件
+func (hm *HistoryManager) SaveToFile() error {
+	if hm.filePath == "" {
+		return fmt.Errorf("文件路径未设置")
+	}
+
+	data, err := json.MarshalIndent(hm.records, "", "  ")
+	if err != nil {
+		return fmt.Errorf("序列化历史记录失败: %v", err)
+	}
+
+	err = ioutil.WriteFile(hm.filePath, data, 0644)
+	if err != nil {
+		return fmt.Errorf("写入文件失败: %v", err)
+	}
+
+	return nil
+}
+
+// LoadFromFile 从文件加载历史记录
+func (hm *HistoryManager) LoadFromFile() error {
+	if hm.filePath == "" {
+		return fmt.Errorf("文件路径未设置")
+	}
+
+	// 检查文件是否存在
+	if _, err := os.Stat(hm.filePath); os.IsNotExist(err) {
+		// 文件不存在，创建空的历史记录
+		hm.records = make([]HistoryRecord, 0)
+		return nil
+	}
+
+	data, err := ioutil.ReadFile(hm.filePath)
+	if err != nil {
+		return fmt.Errorf("读取文件失败: %v", err)
+	}
+
+	err = json.Unmarshal(data, &hm.records)
+	if err != nil {
+		return fmt.Errorf("反序列化历史记录失败: %v", err)
+	}
+
+	// 限制历史记录数量
+	if len(hm.records) > hm.maxSize {
+		hm.records = hm.records[len(hm.records)-hm.maxSize:]
+	}
+
+	return nil
+}
+
+// Search 搜索包含指定关键词的历史记录
+func (hm *HistoryManager) Search(keyword string) []HistoryRecord {
+	var results []HistoryRecord
+
+	for _, record := range hm.records {
+		if contains(record.Expression, keyword) {
+			results = append(results, record)
+		}
+	}
+
+	return results
+}
+
+// GetStatistics 获取历史记录统计信息
+func (hm *HistoryManager) GetStatistics() map[string]interface{} {
+	stats := make(map[string]interface{})
+
+	stats["total_count"] = len(hm.records)
+
+	if len(hm.records) == 0 {
+		return stats
+	}
+
+	// 统计运算符使用频率
+	operatorCount := make(map[string]int)
+	for _, record := range hm.records {
+		for _, char := range record.Expression {
+			switch char {
+			case '+':
+				operatorCount["addition"]++
+			case '-':
+				operatorCount["subtraction"]++
+			case '*':
+				operatorCount["multiplication"]++
+			case '/':
+				operatorCount["division"]++
+			}
+		}
+	}
+	stats["operator_usage"] = operatorCount
+
+	// 最早和最晚的计算时间
+	if len(hm.records) > 0 {
+		earliest := hm.records[0].Timestamp
+		latest := hm.records[0].Timestamp
+
+		for _, record := range hm.records {
+			if record.Timestamp.Before(earliest) {
+				earliest = record.Timestamp
+			}
+			if record.Timestamp.After(latest) {
+				latest = record.Timestamp
+			}
+		}
+
+		stats["earliest_calculation"] = earliest.Format("2006-01-02 15:04:05")
+		stats["latest_calculation"] = latest.Format("2006-01-02 15:04:05")
+	}
+
+	return stats
+}
+
+// ExportToCSV 导出历史记录为 CSV 格式
+func (hm *HistoryManager) ExportToCSV(filePath string) error {
+	var csvContent strings.Builder
+
+	// CSV 头部
+	csvContent.WriteString("Expression,Result,Timestamp\n")
+
+	// 数据行
+	for _, record := range hm.records {
+		csvContent.WriteString(fmt.Sprintf("\"%s\",%g,\"%s\"\n",
+			record.Expression,
+			record.Result,
+			record.Timestamp.Format("2006-01-02 15:04:05")))
+	}
+
+	err := ioutil.WriteFile(filePath, []byte(csvContent.String()), 0644)
+	if err != nil {
+		return fmt.Errorf("导出 CSV 文件失败: %v", err)
+	}
+
+	return nil
+}
+
+// contains 检查字符串是否包含子字符串（忽略大小写）
+func contains(s, substr string) bool {
+	return len(s) >= len(substr) &&
+		(substr == "" ||
+			len(s) > 0 &&
+				(s == substr ||
+					strings.Contains(strings.ToLower(s), strings.ToLower(substr))))
+}